B and Auto

DTC Troubleshooting: B1226 or Indicator B and AUTO

DTC B1226 or DTC indicator B and AUTO:A Short in the In-car Temperature Sensor Circuit

1. Clear the DTC with the HDS.

2. Turn the ignition switch to LOCK (0), and then to ON (II).

3. Do the self-diagnostic function with the HDS Initial Inspection and Diagnostic Overview or climate control unit. Initial Inspection and Diagnostic Overview

4. Check for DTCs.

Is DTC B1226 or B and AUTO indicated?
YES - Go to step 5.

NO - Intermittent failure. Check for loose wires or poor connections on the in-car temperature sensor circuit.


5. Turn the ignition switch to LOCK (0).

6. Remove the in-car temperature sensor, Service and Repair and test it. In-Car Temperature Sensor Test

Is the in-car temperature sensor OK?
YES - Go to step 7.

NO - Replace the in-car temperature sensor.


7. Disconnect climate control unit connectors A (28P) and B (12P).

8. Check for continuity between climate control unit connector A (28P) terminal No. 26 and body ground.

Is there continuity?
YES - Repair a short to body ground in the wire between the climate control unit and the in-car temperature sensor.

NO - Go to step 9.






9. Check for continuity between climate control unit connector A (28P) terminal No. 26 and climate control unit connector B (12P) terminal No. 10.

Is there continuity?
YES - Repair a short in the wires between the climate control unit and the in-car temperature sensor.

NO - Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.